Stencil paper an electric recording and method of producing the same

ABSTRACT

An electrically sensitive stencil sheet is produced by blending a thermoplastic resin, an inorganic conductive fine particle powder and an electroconductive plasticizer which is shaped into a sheet material.

O Umted States Patent 1 1 3,593,660

[72] Inventors Seizo Kineri [52] US. Cl H l01/l28.2, Tokyo; 117/355 Yuzi Harasaki. Shizuoka: Sadamitsu [51] Int. Cl .1 B41n 1/24 Sasaki, Toyohashi. all of Japan [50] Field of Search 1 17/355; [21] Appllflov 665,287 101/1282 [22] Filed Sept. 5, 1967 451 Patented July 20, 1971 References Cited [73] Assignees Tomoegawa Paper Manufacturing UNITED STATES PATENTS p y Limited 2,664,043 12 1953 13611611 1 17/355 x KY0, Java"; 3,283,704 11/1966 Dalton 117/355 x Elem Industrial Company Limited 3,376,810 4/1968 Blake et al. 1 17/355 x Osaka, Japan 2 priority Dem 27, 1962 Primary Examiner-Dav1d Klein 33 1 Japan Attorney-Watson, Cole, Grmdle and Watson [31] 37/59043 Continuation-impart of application Ser. No. 333,171, Dec. 24, 1963, now abandoned.

ABSTRACT: An electrically sensitive stencil sheet is [54] STENCIL PAPER AN ELECTRIC RECORDING AND produced by blending a thermoplastic resin, an inorganic con- METI-IOD 0 F PRODUCING THE SAME 3 Claims, 3 Drawing Figs.

ductive fine particle powder and an electroconductive plasticizer which is shaped into a sheet material.

PATENTEU-JULZOIQIII 3 593 660 Maison, (3)1 GIN d and \Ja'lson ATTORNEYS STENCIL PAPER AN ELECTRIC RECORDING AND METHOD OF PRODUCING THE SAME This application is a continuation-in-part of Ser. No. 333,171 filed-Dec. 24, 1963, now abandoned.

This invention relates to stencil papers for electric recordings comprising electroconductive thermoplastic film and a backing paper.

At the present time, commercially available stencil papers for electric recording consist of paper coated with carbon black and electroconductive film usually composed of polyvinyl chloride, polyvinyl acetate, or a vinyl chloride-vinyl acetate copolymer. in producing the electroconductive thermoplastic film for stencil paper, a fine particle powder of a substance such as carbon black, or tin oxide is added to the thermoplastic resin in an amount between 50 and 100 percent of the weight of the thermoplastic resin. The amount of fine particle powder chosen is determined by the amount of elec trical resistance desired in the final product. This will deter mine the electrically perforatable characteristics of the film. The fine particle powder is mixed with the thermoplastic resin and then calendered into thin sheets of film useful as electroconductive thermoplastic stencil film.

Certain disadvantages are inherent in this electroconductive thermoplastic film for stencil paper. The large amount of fine particle powder required to obtain the proper resistance in the film product substantially reduces the mechanical strength of the film. Further, the inkproofness of such a film in stencil printing after the electric recording often is very poor, and the number of duplicates that can be produced therefrom is limited. In the production of the thermoplastic film it has been found difficult to uniformly disperse the powder in the thermoplastic material; Such uniformity is required since a high concentration of particles at different locations in the film cause irregular electrical resistance in the film which during use produce smoke and chips which clog the perforated film during recording, and make the recording obscure.

A primary object of the present invention is to eliminate the above-mentioned defects of the conventional electroconductive thermoplastic stencil film by combining an electroconductive plasticizer with the fine particle powder of a conduc' tive substance in the thermoplastic film.

A secondary object of the present invention is to provide an electroconductive thermoplastic stencil film for electric recording which is high in mechanical strength and easily produced.

A third object of the present invention is to provide an electroconductive thermoplastic stencil film for electric recording having a high inkproofness and producing no chip in per forated records.

A still further object of the present invention is to provide an electroconductive thermoplastic stencil film for electric recording wherein records can be perforated with a substantially smaller current at a substantially higher voltage than has been possible previously.

Briefly,in accordance with the present invention, to 35 parts by weight of a fine particle powder of a conductive substance such as carbon black, and graphite, and l to 20 parts by weight of an electroconductive plasticizer such as a dodecylamid-propyl-diethyl hydroxy propyl ammonium nitrate; are added to about 100 parts by weight of a thermoplastic resin which is easily worked into a film. Examples of such thermoplastic resins are polyvinyl chloride, polyvinyl acetate, and vinyl chloride-vinyl acetate copolymer. The mixture of conductive powder, plasticizer and thermoplastic resin is first jelled by passing it through hot kneading rolls and then formed into the thin film required for electroconductive thermoplastic stencil film by either passing thejelled mixture through heated calender rolls or by pelleting the'jelle'd mixture and feeding it to anextruder. The'resultant film shouldbe about 20 microns thick.

Suitable electroconductive plasticizer agents may contain from about 35 parts of dioctyl phthalate or the like. Such a mixture may contain about 60 percent dodecyl-amid-propyldiethyl hydroxy propyl ammonium nitrate c1115 (011E250()NIICHZCIIQCHTJTI -cnz ouotmNot can 01-1 and about 40 percent of dioctyl phthalate (C H (COOCH CH (C H C.H,,),). The quaternary ammonium salt gives the mixture its electroconductive properties.

in the accompanying drawings, HO. .1 is a perspective view of a stencil paper for electric recording according to the present invention;

FIG. 2 is a view showing a mechanism used when an electric recording is made on a stencil paper;

FIG. 3 is a view showing an embodiment of a mechanism for electrically perforating a stencil paper of the present invention so as to make it the same as a pattern to be reproduced.

Referring to FlG. l, the electroconductive thermoplastic film l is used in combination with a supporting paper base member 2 which is approximately microns thick and is subjected to low resistance treatment so as to act as a return electrode. Fixed to each end of the electroconductive thermoplastic stencil film l and the supporting paper base member 2 is a holding paper member 3 which serves to secure the electrically perforated stencil sheet on a rotary stencil printer. The electric recording stencil paper having a pattern recorded thereon can be used to reproduce this pattern by means of the mechanism shown in FIG. 3 or a remote control device such as is disclosed in U.S. Pat. No. 2,664,043.

Referring to FIG, 3, 5 is an electric recording stencil paper comprising electroconductive film containing an electroconductive plasticizer and base paper treated to give it low electrical resistance; 7 is a light spot focused on a pattern 6; 8 is a scanning box and 9 is a photoelectric tube. 10 is an amplifier controlled by the photoelectric tube which in return controls a stylus 11. The pattern 6 and the stencil paper 5 are driven simultaneously by means of electric motor 12. The operation of the mechanism is well known and the method employed is fully disclosed in U.S. Pat. No. 2,664,043.

FIG. 2 shows the mechanism for carrying out the electric recording on the stencil paper. I is an electroconductive thermoplastic stencil film; 2 is a supporting base member and 11 is the stylus used for recording the pattern on the stencil paper.

in the method according to the present invention, the fine particles of the conductive substance and the electroconductive plasticizer are mixed together and are added to the thermoplastic material. The proportion of fine particles of the conductive substance, being 10 to 35 parts by weight, is substantially less than in the presently available commercial product. Therefore, the mechanical strength of the stencil paper will remain very high. The result is that substantially more duplicates can be produced from a single stencil than was previously possible. A further advantage of stencil electroconductive thermoplastic stencil film having a substantially smaller proportion of fine particles of conductive material is that there is no chance of producingsmoke and chips which clog the perforated parts during perforation of the stencil. Clearer duplicate records can therefore be produced.

By using the electroconductiveplasticizer, the dispersion of the fine particles of the conductive material in the thermoplastic material can be accelerated. The time required for mixing the material constituting the electroconductive thermoplastic stencil film is remarkably shortened as compared with previously known methods of producing electroconductive thermoplastic stencil film. For example, whereas it took 15 to 24 hours of mixing by the conventional method using the electroconductive plasticizer, this mixing time can be reduced to 5 to 10 hours using the same conventional mixer.

By carefully controlling the relative proportions of component materials in the thermoplastic :resin, it is possible to regulate the specific surface resistance of the electroconductive thermoplastic stencil film product which may range between l and ohms. The resistance range of the conventionally available electroconductive thermoplastic stencil films ranges between 10 and 10 ohms. The resistance of the improved electroconductive thennoplastic stencil film being considerably higher, it follows that recordings can be made with a smaller current at a higher voltage than was previously possible. The advantage of this is that the possibility of circular perforations in the stencil is avoided and the resultant clogging of these perforations with ink is therefore eliminated. The presently available commercial electroconductive thermoplastic stencil film product requires a recording current of approximately 40 milliamperes at an impressing voltage of I50 volts. Under such conditions it is not unusual to find parts of the stencil obscured. In the product of the present invention with a recording current of i5 milliamperes at an impressing voltage of 450 volts, very clear records are obtained. The following are specific examples of the method of preparing electroconductive thermoplastic stencil film.

EXAMPLE I I00 parts of polyvinyl chloride resin having a polymerization degree of 1,000, 30 parts of acetylene black, and 1.2 parts of lead stearate powder were stirred and mixed for about 30 minutes after which 35 parts of dioctyl phthalate and 3.5 parts of a mixture of 60 percent of dodecyI-amid-propyl-diethyl hydroxy propyl ammonium nitrate and 40 percent dioctyl phthalate were added. The mixture was stirred and mixed for about 7 hours after which it was left standing to age for 12 hours. It was then jelled with hot rolls at I60 to 170 C. and then rolled with precision calender rolls at l70 to 175 C. forming a film microns thick. The stencil film product had a tensile strength of 2.4 kg./mm. an elongation of 88 percent. The specific surface resistance was 8X10 ohms.

When this electroconductive thermoplastic stencil film was placed on a conductive base paper of a specific surface resistance of 600 ohms and recording was made with an electric power consumption of 4 watts, the clarity of the stencil record was very high. The perforations did not become clogged with ink during duplication. Also, the stencil film was softer than those commercially available and therefore the duplicating capacity was considerably greater. The mixing time was a total of about 7 hours which reduced by about one-half the time required for the commercially available product. Production efficiency therefore was doubled.

EXAMPLE 2 I00 parts of polyvinyl chloride resin having a polymerization degree of 1,000, parts of acetylene black and L2 parts of lead stearate powder were stirred and mixed for about minutes after which 30 parts of dioctyl phthalate and 7 parts of a mixture of 60 percent dodecylamid-propyl-diethyl hydroxy propyl ammonium nitrate and 40 percent of dioctyl phthalate were added. Subsequent treatment was identical to that in Example 1. V

The electroconductive thermoplastic stencil film product had a tensile strength of 2.8 kg./mm., an elongation of 83 percent and a specific surface resistance of 6X10" ohms. Other characteristics such as the recording clarity, softness and duplicating capacity were identical with those characteristics of the product produced in Example 1.

EXAMPLE 3 100 parts of a vinyl chloride-vinyl acetate copolymer resin containing percent vinyl chloride and having a polymerization degree of 800, 23 parts of acetylene black, 2 parts of dibutyl tin stearate, 1 part of barium stearate, and 1 part of cadmium stearate were stirred and mixed for about 30 minutes after which 25 parts of dioctyl phthalate and 5 parts of a mixture of about 60 percent dodecyl-amid-propyl-diethyl hydrox propyl ammonium nitrate and about 40 percent dioctyl pht alate were added. The subsequent treatment was identical to that in Example I.

The electroconductive thermoplastic stencil film produced therefrom had a tensile strength of 2.8 kg./mm. an elongation of 82 percent and a specific surface resistance of 3.5 l0 ohms. Other characteristics were identical to the product produced in Example I.

EXAMPLE 4 100 parts of a vinyl chloride-vinyl acetate copolymer resin containing percent vinyl chloride and having a polymerization degree of 1,150, 27 parts ofa conductive furnace black, 1 part of cadmium stearate and 1 part of barium stearate were stirred and mixed for about 30 minutes after which 30 parts of dioctyl phthalate and 5 parts of a mixture of about 60 percent dodecyl-amid-propyl-diethyl hydroxy propyl ammonium nitrate and about 40 percent of dioctyl phthalate were added. Subsequent treatment was identical to that in Example I.

The thus obtained electroconductive thermoplastic stencil film had a tensile strength of 3.0 kg./mm. an elongation of 65 percent and a specific surface resistance of 3.2 l0 ohms. Other characteristics of the product were identical to the product produced in Example 1.

The above examples demonstrate the marked improvement in quality of electroconductive thermoplastic stencil film as compared with the prior art. By incorporating into the thermoplastic material an electroconductive plasticizer it becomes possible to substantially reduce the amount of conductive inorganic powder which must be incorporated in the thermoplastic resin. Production rate is nearly doubled and the product produced is substantially improved as to strength and the quality of the stencil produced from the film.

What we claim is:

I. An electric recording stencil paper comprising an electroconductive thermoplastic resin film and a base paper of low electrical resistance, wherein said film has a thickness of about 20 microns and a specific surface resistance ranging between l0 ohms and 10 ohms, and contains about parts of a thermoplastic resin, from about 10 to about 35 parts of a fine- 1y divided conductive powder, and as a plasticizer from about 25 parts to about 35 parts of dioctyl phthalate and from about 3.5 to about 7 parts of a mixture containing about 60 percent dodecyl-amid-pi'opyl-diethyl hydroxy propyl ammonium nitrate and about 40 percent dioctyl phthalate.

2. An electric recording stencil paper as in claim 1 wherein said thermoplastic resin is selected from the group consisting of polyvinyl chloride, polyvinyl acetate, and copolymers of vinyl chloride and vinyl acetate.

3. An electric recording stencil paper as in claim 1 wherein said finely divided conductive powder is selected from the group consisting of carbon black and graphite. 

2. An electric recording stencil paper as in claim 1 wherein said thermoplastic resin is selected from the group consisting of polyvinyl chloride, polyvinyl acetate, and copolymers of vinyl chloride and vinyl acetate.
 3. An electric recording stencil paper as in claim 1 wherein said finely divided conductive powder is selected from the group consisting of carbon black and graphite. 